Binary Tree Node Structure in DSA Javascript - Execution Trace

Concept Flow - Binary Tree Node Structure

Create new node

↓

Assign data value

↓

Set left child pointer to null

↓

Set right child pointer to null

↓

Node ready for use in tree

This flow shows how a binary tree node is created with data and two child pointers initialized to null.

Execution Sample

DSA Javascript

class Node {
  constructor(data) {
    this.data = data;
    this.left = null;
    this.right = null;
  }
}

This code defines a binary tree node with data and two pointers for left and right children.

Execution Table

Step	Operation	Node Data	Left Pointer	Right Pointer	Visual State
1	Create node with data=10	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │right:∅ │ └────────┘
2	Node ready for use	10	null	null	┌────────┐ │ data:10│ │ left:∅ │ │right:∅ │ └────────┘

💡 Node creation complete with data=10 and both child pointers set to null.

Variable Tracker

Variable	Start	After Step 1	Final
node.data	undefined	10	10
node.left	undefined	null	null
node.right	undefined	null	null

Key Moments - 2 Insights

Why are left and right pointers set to null initially?

Because the node starts without children, setting left and right to null shows no child nodes exist yet, as seen in execution_table step 1.

What does the 'data' field represent in the node?

It holds the value stored in the node, which is 10 in the example, shown in execution_table step 1 under Node Data.

Visual Quiz - 3 Questions

Look at the execution_table at step 1, what is the value of node.left?

A 10

B undefined

C null

D node.right

💡 Hint

Check the 'Left Pointer' column in execution_table row for step 1.

At which step is the node fully created with data and pointers set?

A Step 1

B Step 2

C Step 3

D Step 0

💡 Hint

Look at the 'Operation' column and final visual state in execution_table.

If we add a left child node, which pointer changes from null?

A node.left

B node.right

C node.data

D node itself

💡 Hint

Recall that left and right pointers hold child nodes; left child changes node.left.

Concept Snapshot

Binary Tree Node Structure:
- Each node stores data.
- Has two pointers: left and right.
- Both pointers start as null (no children).
- Used to build binary trees by linking nodes.
- Example: node = {data:10, left:null, right:null}

Full Transcript

A binary tree node is created by assigning a data value and initializing two pointers, left and right, to null. This means the node has no children yet. The code example shows a class Node with a constructor setting these fields. The execution table traces the creation step by step, showing the node's data and pointers. Key points include understanding why pointers start as null and what the data field holds. The visual quiz tests knowledge of pointer values and node creation steps.